SAN CARLOS -- Amid fresh concerns about the safety of its natural gas pipeline, PG&E on Monday shut down a nearly 4-mile-long section that lies under the city of San Carlos between Highway 101 and Interstate 280.

The utility undertook the action in response to a San Mateo County judge's order following disclosures about faulty record keeping and complaints from city officials.

"The line is isolated," PG&E spokeswoman Brittany Chord said Monday. "We reduced the pressure in the line."

While no longer connected to the PG&E gas delivery system, some natural gas remained in the line, she said. The line, identified as Line 147, normally operates at 300 pounds per square inch, but PG&E reduced that to 100 psi.

San Carlos officials pressed for a legal ruling to shut down the line after it was disclosed a PG&E engineer had raised questions about its safety. PG&E previously had revealed its records about the line's pressure capacity were inaccurate.

"We have been frustrated, confused -- certainly, above all, we have been concerned for the safety of the folks in town who live along Line 147," San Carlos City Manager Jeff Maltbie said in an interview.

San Carlos officials said PG&E's chief regulator, the state Public Utilities Commission, has assured the city that the PUC is working on options for the pipeline that the commission will present to San Carlos.

"Line 147 is an important element in our system," said Chord. "The line helps ensure that we meet demand, especially the peak demand in the winter."

City officials believe PG&E intends to seek a ruling to vacate the order for the line's shutdown. PG&E wouldn't discuss its legal strategy, saying only it is following the court process.

"Right now, there are still a lot of unanswered questions about PG&E's gas system," said Karen Paull, interim chief counsel for the Office of Ratepayer Advocates at the PUC. "We are very concerned about whether this kind of problem is appearing elsewhere in the PG&E gas system. Is there a widespread problem with PG&E's records? Is there a problem with pipe characteristics?"

Following the 2010 explosion in San Bruno that killed eight, investigators determined that inaccurate records and flaws in maintenance procedures contributed to the fatal blast. PG&E undertook an array of efforts to forestall another catastrophe, including pressure testing numerous pipelines and updating its records for the pipes. In September 2011, Line 147 in San Carlos was among those tested with water at high pressure.

Despite its efforts, some glitches persist. PG&E revealed that it provided the PUC with inaccurate records about the maximum pressure allowable for Line 147. The utility subsequently disclosed that an engineer had warned that the hydro testing could have weakened the pipe.

"These latest problems highlight the fact that PG&E's records are abysmal," said Thomas Long, legal director for The Utility Reform Network, a consumer group. "They show that PG&E is putting up a false front to the public. They are saying they have a good handle on the situation. But they don't."

San Francisco-based PG&E conducted a metallurgical analysis of Line 147 after the engineer raised the new issues. The report determined the 3.8-mile line had not suffered a crack.

"We continue to encourage employees to raise issues and concerns," Chord said. "This is part of our safety culture."